There are many situations where toxic heavy metals such as mercury are contained in fluid streams (both gaseous and liquid). For example, produced water from offshore oil platforms can have mercury levels that range from less than 100 parts per billion (ppb) in the gulf of Mexico to about 2,000 ppb in the Gulf of Thailand. Complicating matters is that in many applications, sediments and other undesirable particles may also be present in many environmental applications. Removal of such toxic heavy metals to acceptable levels, while the subject of a long felt desire and need, has been typically satisfied with either inadequate, difficult and/or expensive solutions.
The use of particles of self-assembled monolayers on mesoporous supports (SAMMS) have shown to have substantial capabilities for adsorbing toxic metal contaminants. An example SAMMS material is disclosed in U.S. Pat. Nos. 6,326,326; 6,531,224; 6,733,835; 6,753,038; and 6,846,554, the entire disclosures of which are hereby incorporated by reference. One type of SAMMS is thiol-SAMMS, in which the mesoporous material is functionalized with molecules of a thiol group. Thiol-SAMMS is commercially available as particles in a powder-like form from Steward Environmental Solutions, LLC of Chattanooga, Tenn. The SAMMS powder material typically can have different particle diameters that are typically in the range of between about 30 and about 200 micron (Steward Environmental Solutions, LLC advertises an average diameter of 40 micron). On the one hand, providing a larger diameter is beneficial from a fluid flow standpoint in that a fixed bed of powder material allows for greater fluid flow. However, larger adsorbent particles do not have as much effective available surface area for contaminant adsorption. While smaller SAMMS powder material provides for greater effective surface area and adsorption potential, packing such small powder is highly restrictive to fluid flow and can create difficulties from a fluid flow standpoint.
SAMMS has extremely fast kinetics and a sizeable loading capacity (e.g. 0.4-0.6 grams HG/gram of THIOL-Samms adsorbent for terminal HG concentration of 100-200 ppm). Additionally, SAMMS works through covalently bonding for reliable retention of toxic metal contaminant. SAMMS typically has a bulk density of between approximately 0.2 g/cc and 0.4 g/cc.
Various examples have been disclosed for using such SAMMS powder particles. For example, various SAMMS filtration systems are disclosed in U.S. Patent Publication Nos. US 2007/0295204 A1 entitled “Systems And Methods For Flow-Through Treatment Of Contaminated Fluid”; US 2007/0262027 A1 entitled “Layered Filter For Treatment Of Contaminated Fluids”; US 2007/0262025 A1 entitled “Canister For Treatment Of Contaminated Fluids”; US 2007/0256981 A1 entitled “Composite Adsorbent Block For The Treatment of Contaminated Fluids”; and US 2007/0256980 entitled “Countercurrent Systems And Methods For Treatment Of Contaminated Fluids”. All of these patent publications are incorporated by reference in their entireties as the present invention pertains to improvements upon these contaminant adsorbent technologies.